Preparation And Research Of Acrylamide Copolymer Based On "Dual Anion" And "Dual Cation" Functional Monomers

Polyacrylamide（PAM）is classified as homopolymer of acrylamide（AM）,copolymer of AM with other ionic monomers,and polyacrylamide derivatives.With the different types of copolymer,the performance of polyacrylamide shows different characteristics,such as flocculation,thickening,shear resistance,resistance reduction and dispersion.Polyacrylamide is known as environment-friendly"Industrial auxiliaries",in the field of flocculation,as a flocculant to treat sewage to improve water quality;In the field of agriculture,as a water retaining agent for soil improvement and dry agriculture development,improve the utilization rate of water resources;It can also be used as an auxiliary for oil extraction.In this paper,acrylamide（AM）and biotype polycarboxylic polymerizable monomer itaconic acid（IA）were used as the main body,and different types of cationic structural monomers（SC_n and DC₈）were introduced into the polymer backbone to explore the structure and application properties of functional polyacrylamide.In the synthesis method,the primary redox initiator and the secondary azo initiator were used as the composite initiator system,and the influence of initiator dosage,monomer concentration,system pH value and other factors on the viscosity of the polymerization product was explored by aqueous polymerization.The obtained products were characterized analytically by Fourier infrared spectroscopy（FT-IR）and nuclear magnetic hydrogen spectroscopy（¹H-NMR）.The synthesized products P（AM-IA）,P（AM-IA-SC_n）and P（AM-IA-DC₈）were applied to laboratory experiments to simulate sewage flocculation,polymer swelling and solution properties.Specific research conclusions are as follows:First,the copolymer P（AM-IA）was prepared using AM and IA as reactants.Using aqueous polymerization method,using compound initiator polymerization,in-depth discussion of IA monomer content,redox initiator（sodium bisulfite and ammonium persulfate）and secondary initiator 2,2’-azobis（2-imidazoline）dihydrochloride（V-44）dosage and pH value of polymerization reaction conditions,after polymerization process test,The optimal characteristic viscosity of anionic P（AM-IA）was as follows:the monomer concentration was 25%,the molar ratio of AM to IA was 9:1,the amount of redox initiator accounted for 0.04%of the monomer mass,the amount of secondary initiator V-44 was 0.14%of the monomer mass,the pH value of the reaction system was 7-8,and the characteristic viscosity of the product was 15.03 d L/g.The crosslinked P（AM-IA）with AM,IA and cross-linking agent N,N’-Methylenebis（2-propenamide）（MBA）was also synthesized and characterized by FT-IR,¹H-NMR and scanning electron microscopy.P（AM-IA）in kaolin suspension simulated wastewater experiment,with the mono-carboxy P（AM-AA）with the same characteristic viscosity and monomer ratio as the reference,the amount of polymeric aluminum chloride（PAC）was 30 mg/L,the amount of P（AM-IA）was 5 mg/L,and the pH value of the system was 7-9,the transmitrate of the supernatant could reach 95.72%.The flocculation effect was better than that of mono-carboxy P（AM-AA）.For cross-linked P（AM-IA）,the maximum water absorption of dicarboxylic P（AM-IA）was 520 g/g,which was 2-3times of that of mono-carboxy P（AM-AA）.After five times of drying and resorption,the cross-linked P（AM-IA）had a water absorption fold of 434 g/g,while the mono-carboxy P（AM-AA）had a maximum water absorption fold of only 196 g/g.The results showed that the water absorption and water retention performance of dicarboxylic P（AM-IA）was better than that of mono-carboxy P（AM-AA）.Secondly,A series of monocationic monomer SC_n（n=1,4,8,12,16）with different lengths of hydrophobic chain segments were synthesized.Amphoteric P（AM-IA-SC_n）was prepared by aqueous polymerization using AM and IA as copolymerization backbones.Taking SC₈ as an example,the single factor variable method was selected and the process parameters were screened.The optimal polymer formula was obtained as follows:the monomer concentration was 25%,initiation temperature was 40℃,n（AM）:n（IA）:n（SC₈）=8.2:1:0.8,the dosage of initiator V-44 was 0.2%of monomer mass,and the pH value was 7-8.The characteristic viscosity of polymer P（AM-IA-SC₈）was 11.7 d L/g.The polymerization steps of other monomers are the same,so the description will not be repeated.Cross-linked P（AM-IA-SC_n）was synthesized with AM,IA,crosslinking agent MBA and cationic monomer SC_n as reactants.The product was characterized by FT-IR and ¹H-NMR,and simulated wastewater（kaolin suspension with different pH values）and sludge settlement experiments were conducted.The experimental results showed that the longer the hydrophobic chain contained in the side group of SC_n monomer,the better the settlement effect on kaolin and sludge,and the light transmission rate of superclear liquid reached about 90%when the pH was 1-9.However,anionic polyacrylamide has the best effect only when pH is7-9.According to swelling experiment,the maximum water absorption rate of the cross-linked P（AM-IA-SC_n）polymer is 900-1100 g/g after the addition of cationic functional monomers,which is nearly twice that of P（AM-IA）.At the same time,after five drying and re-absorption,The water absorption ratio of cross-linked P（AM-IA-SC_n）was 835 g/g,which was twice that of P（AM-IA）,indicating that amphotic P（AM-IA-SC_n）showed strong water absorption and reuse ability.Thirdly,Gemini hydrophobic monomer 2-（acryloxy）-tetramethyl-nonyl-octylpropane-1,3-diammonium bromide（DC₈）was copolymerized with AM and IA,and P（AM-IA-DC₈）was obtained by micellitization.For optimization of polymerization process,the formula of polymer with maximum viscosity is:The concentration of the monomer was 30%,the molar ratio of the monomer was AM:IA:DC₈=8.75:1:0.25,the amount of V-44 accounted for 0.15%of the total mass of the monomer,the pH value of the reaction system was 7-8,and the characteristic viscosity of the copolymer P（AM-IA-DC₈）was 8.5d L/g.The hydrophobic monomer and polymer were successfully prepared by FT-IR and ¹H-NMR analysis.At the same time,the temperature and salt resistance of P（AM-IA-DC₈）solution was tested.The experimental results show that the viscosity retention rate of P（AM-IA-DC₈）is 40.9%when the polymer concentration is 5 g/L and the temperature is 90℃.In terms of salt resistance,the viscosity of polymer P（AM-IA-DC₈）solution decreased gently when the concentration of sodium chloride was 3000-8000 mg/L due to the anti-electrolyte effect of polymer.The viscosity tends to be stable when the concentration of sodium chloride is 8000-15000 mg/L.The viscosity retention rates of polymer P（AM-IA）,P（AM-IA-SC₈）and P（AM-IA-DC₈）were 9.3%,20.6%and 29.3%,respectively.In terms of shear resistance,continuous shear and alternating shear experiments show that polymer P（AM-IA-DC₈）has good shear stability and recovery.